1 创建对象
Javascript 支持对象的概率。有多种方法可以用来创建对象。
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Javascript Object </title> </head> <body> <script> var myData = new Object(); myData.name = "Luka"; myData.weather = "sunny"; document.writeln("Hello "+myData.name+"."); document.writeln("Today is "+myData.weather+".") </script> </body> </html>
输出结果：
Hello Luka. Today is sunny.
1.1 使用对象字面量
用对象字面向量的方式可以一口气定义一个对象及其属性。
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Javascript Object </title> </head> <body> <script> var myData = { name:"Luka", weather:"sunny" }; document.writeln("Hello "+myData.name+"."); document.writeln("Today is "+myData.weather+".") </script> </body> </html>
1.2 将函数用作方法
对象可以添加属性，也能添加函数。属于一个对象的函数称为其方法。
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Javascript Object </title> </head> <body> <script> var myData = { name:"Luka", weather:"sunny", printMessage:function(){ document.writeln("Hello "+this.name+"."); document.writeln("Today is "+this.weather+".") } }; myData.printMessage(); </script> </body> </html>
2 使用对象
创建对象后，可以用来做许多事。
2.1 读取和修改属性值
对象最显而易见的操作是读取或修改属性值
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Javascript Object </title> </head> <body> <script> var myData = { name:"Luka", weather:"sunny" }; myData.name="Joe"; myData["weather"]="raining"; document.writeln("Hello "+myData.name+"."); document.writeln("It is "+myData["weather"]+"."); </script> </body> </html>
输出结果：
Hello Joe. It is raining.
2.2 枚举对象
要枚举对象属性可以使用 for...in 语句。
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Javascript Object </title> </head> <body> <script> var myData = { name:"Luka", weather:"sunny", printMessages:function(){ document.writeln("Hello "+this.name+". "); document.writeln("Today is "+this.weather+"."); } }; for(var prop in myData){ document.writeln("Name: "+prop+" Value: "+myData[prop]+"<br />"); } </script> </body> </html>
显示结果：
Name:name Value:Luka
Name:weather Value:sunny
Name:printMessages Value:function (){ document.writeln("Hello "+this.name+". "); document.writeln("Today is "+this.weather+"."); }
2.3 增删属性和方法
就算是用对象字面量生成的对象，也可以为其定义新属性。
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Javascript Object </title> </head> <body> <script> var myData = { name:"Luka", weather:"sunny" }; //为对象添加新属性 myData.dayOfWeek = "Monday"; //为对象添加新方法 myData.sayHello = function(){ document.writeln("Hello"); }; //对象的属性和方法可以用 delete 关键字删除 delete myData.name; delete myData["weather"]; delete myData.sayHello; </script> </body> </html>
2.4 判断对象是否具有某个属性
可以用 in 表达式判断对象是否具有某个对象。
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Javascript Object </title> </head> <body> <script> var myData = { name:"Luka", weather:"sunny" }; var hasName = "name" in myData; var hasDate = "date" in myData; document.writeln("HasName: "+hasName+"<br />"); document.writeln("HasDate: "+hasDate); </script> </body> </html>
输出结果：
HasName: true
HasDate: false
本文转自叶超Luka博客园博客，原文链接：http://www.cnblogs.com/yc-755909659/p/5928005.html，如需转载请自行联系原作者
